我有一个SQL查询，它将子查询作为左连接的参数。
SELECT tblfLeaseDetail.Lease_Detail_ID,
tblfPayment.Payment_Date,
tblfAuthorization.Authorized,
tblvVendor.Vendor_Name,
tblvCounty.County
FROM tblfLeaseDetail
LEFT
JOIN tblfPayment
ON tblfPayment.Lease_Detail_ID = tblfLeaseDetail.Lease_Detail_ID
AND tblfPayment.Payment_ID =
( SELECT TOP 1
Payment_ID
FROM tblfPayment
WHERE tblfPayment.Lease_Detail_ID = tblfLeaseDetail.Lease_Detail_ID
ORDER BY Payment_Date DESC
)
LEFT
JOIN tblfAuthorization
ON tblfAuthorization.Lease_Detail_ID = tblfLeaseDetail.Lease_Detail_ID
AND tblfAuthorization.Authorization_ID =
( SELECT TOP 1
Authorization_ID
FROM tblfAuthorization
WHERE tblfAuthorization.Lease_Detail_ID = tblfLeaseDetail.Lease_Detail_ID
ORDER BY Authorized_Date DESC
)
LEFT JOIN tblvVendor
on tblvVendor.Vendor_ID = tblfLeaseDetail.Vendor_ID
LEFT JOIN tblvCounty
on tblvCounty.County_ID = tblfLeaseDetail.County_ID
我试图将其转换为LINQ。到目前为止，这就是我所做的：
var leaseList = (from l in leases.tblfLeaseDetails
join a in leases.tblfAuthorizations on l.Lease_Detail_ID equals a.Lease_Detail_ID into la
from jla in
(from aj in leases.tblfAuthorizations
where aj.Lease_Detail_ID == l.Lease_Detail_ID
orderby aj.Authorized_Date descending
select aj.Authorization_ID).Take(1).DefaultIfEmpty()
join p in leases.tblfPayments on l.Lease_Detail_ID equals p.Lease_Detail_ID into lp
from jlp in
(from pj in leases.tblfPayments
where pj.Lease_Detail_ID == l.Lease_Detail_ID
orderby pj.Payment_Date descending
select pj.Payment_ID).Take(1).DefaultIfEmpty()
join v in leases.tblvVendors on l.Vendor_ID equals v.Vendor_ID into lv
from jlv in lv.DefaultIfEmpty()
join c in leases.tblvCounties on l.County_ID equals c.County_ID into lc
from jlc in lc.DefaultIfEmpty()
select new LeaseViewModel()
{
Lease_Detail_ID = l.Lease_Detail_ID,
Vendor_Name = jlv.Vendor_Name,
County = jlc.County,
Authorization = jla.Authorized,
Payment_Date = jlp.Payment_Date
}).Distinct()
这会在 jla.Authorized 和 jlp.Payment_Date 中返回错误：
＆＃39; INT＆＃39;不包含＆＃39;授权＆＃39;的定义并且没有延期方法＆＃39;授权＆＃39;接受类型＆＃39; int＆＃39;的第一个参数可以找到
Payment_Date也有同样的错误。
为什么jla和jlp被认为是整数？如何使此查询有效？
修改
这是最终且有效的LINQ查询：
var leaseList = (from l in leases.tblfLeaseDetails
join a in leases.tblfAuthorizations on l.Lease_Detail_ID equals a.Lease_Detail_ID into la
from jla in la.DefaultIfEmpty()
where jla.Authorization_ID == (from aj in leases.tblfAuthorizations
where aj.Lease_Detail_ID == l.Lease_Detail_ID
orderby aj.Authorized_Date descending
select aj.Authorization_ID).Take(1).FirstOrDefault()
join p in leases.tblfPayments on l.Lease_Detail_ID equals p.Lease_Detail_ID into lp
from jlp in lp.DefaultIfEmpty()
where jlp.Payment_ID == (from pj in leases.tblfPayments
where pj.Lease_Detail_ID == l.Lease_Detail_ID
orderby pj.Payment_Date descending
select pj.Payment_ID).Take(1).FirstOrDefault()
join v in leases.tblvVendors on l.Vendor_ID equals v.Vendor_ID into lv
from jlv in lv.DefaultIfEmpty()
join c in leases.tblvCounties on l.County_ID equals c.County_ID into lc
from jlc in lc.DefaultIfEmpty()
select new LeaseViewModel()
{
Lease_Detail_ID = l.Lease_Detail_ID,
Lease_ID = l.Lease_ID,
XRef_Lease_ID = l.XRef_Lease_ID,
Vendor_Name = jlv.Vendor_Name,
Description = l.Description,
County = jlc.County,
Amount = l.Amount,
Payment_Due_Date = l.Payment_Due_Date,
Lease_Type = l.Lease_Type.ToString(),
Location_ID = l.Location_ID,
Active = l.Active,
Expiration_Date = l.Expiration_Date,
Authorization = jla.Authorized,
Payment_Date = jlp.Payment_Date
}).Distinct();
答案 0 :(得分：1)
这是因为您分别在jla和jlp中选择了int类型的Authorization_ID和Payment_ID。尝试以下查询，让我知道它是如何工作的。
bool rval = false;
IntPtr hWinStaOrig, hWinSta, hDesktop;
Win32.DEVMODE dm = GetDevMode();
Win32.DISPLAY_DEVICE d = new Win32.DISPLAY_DEVICE();
d.cb = Marshal.SizeOf(d);
if (Win32.EnumDisplayDevices(null, deviceID, ref d, 0))
{
if (((d.StateFlags & Win32.DisplayDeviceStateFlags.AttachedToDesktop) != 0) &&
((d.StateFlags & Win32.DisplayDeviceStateFlags.PrimaryDevice) == 0))
{
if (Win32.EnumDisplaySettingsEx(d.DeviceName, Win32.ENUM_CURRENT_SETTINGS, ref dm, 0) != 0)
{
dm.dmPelsWidth = 0;
dm.dmPelsHeight = 0;
dm.dmFields = Win32.DmFlags.DM_POSITION | Win32.DmFlags.DM_PELSWIDTH | Win32.DmFlags.DM_PELSHEIGHT;
if (Win32.ChangeDisplaySettingsEx(
d.DeviceName,
ref dm,
IntPtr.Zero,
Win32.ChangeDisplaySettingsFlags.CDS_UPDATEREGISTRY | Win32.ChangeDisplaySettingsFlags.CDS_RESET, // | Win32.ChangeDisplaySettingsFlags.CDS_GLOBAL ,
IntPtr.Zero
) == (int)Win32.DISP_CHANGE.SUCCESSFUL)
{
hWinStaOrig = Win32.GetProcessWindowStation();
hWinSta = Win32.CreateWindowStation("MyWinSta", Win32.CWF_CREATE_ONLY,
Win32.ACCESS_MASK.WINSTA_ALL_ACCESS | Win32.ACCESS_MASK.STANDARD_RIGHTS_ALL,
0);
if (hWinSta != IntPtr.Zero)
{
if (Win32.SetProcessWindowStation(hWinSta))
{
hDesktop = Win32.CreateDesktop("MyDesktop", null, null, Win32.DF_ALLOWOTHERACCOUNTHOOK, Win32.ACCESS_MASK.MAXIMUM_ALLOWED, 0);
if (hDesktop != IntPtr.Zero)
{
if (AttachDisplayDevice(deviceID))
{
IntPtr hDC = Gdi32.CreateDC(d.DeviceName, null, null, IntPtr.Zero);
if (hDC != IntPtr.Zero)
{
Win32.RECT r;
r.left = 10;
r.top = 10;
r.right = 400;
r.bottom = 300;
Gdi32.SetTextColor(hDC, 0xffffff);
Gdi32.SetBkColor(hDC, 0x0);
if (Win32.DrawText(hDC, "Hello, Bozo!", -1, ref r, Win32.DT_CENTER | Win32.DT_VCENTER | Win32.DT_SINGLELINE) == 0)
{
Console.WriteLine("DrawText failed!");
}
Console.Write("Press Enter to Continue...");
Console.ReadLine();
Gdi32.DeleteDC(hDC);
}
DetachDisplayDevice(deviceID);
}
if (!Win32.CloseDesktop(hDesktop))
{
Error("CloseDesktop");
}
}
else
{
Error("CreateDesktop");
}
if (!Win32.SetProcessWindowStation(hWinStaOrig))
{
Error("SetProcessWindowStation Failed!");
}
}
rval = Win32.CloseWindowStation(hWinSta);
}
AttachDisplayDevice(deviceID);
}
}
}
}
return rval;
}